A method of forming a coating of a polymer-based paint composition on a substrate (1) is disclosed. The method is based on the use of pellets (13) rather than solid blocks of the paint composition. The method includes pre-heating a substrate (1) to a temperature that is above the glass transition temperature of the polymer of the paint composition and supplying pellets (13) of the paint composition to the surface of the substrate (1) whereby the pellets (13) progressively melt into a liquid state. Thereafter, the method includes forming a coating of the liquid paint composition on the substrate surface (1) and converting the liquid coating into a solid coating of the paint composition.